Benzotriazole, mercaptobenzothiazole and tolyltriazole are well known copper corrosion inhibitors. For example, see U.S. Pat. No. 4,675,158 and the references cited therein. This patent discloses the use of tolyltriazole/mercaptobenzothiazole compositions as copper corrosion inhibitors. Also, see U.S. Pat. No. 4,744,950, which discloses the use of lower (C.sub.3 -C.sub.6) alkylbenzotriazoles as corrosion inhibitors, and corresponding EPO application No. 85304467.5.
U.S. Pat. No. 4,338,209 discloses metal corrosion inhibitors which contain one or more of mercaptobenzothiazole, tolyltriazole and benzotriazole. Examples of formulations containing benzotriazole and tolyltriazole and formulations containing mercaptobenzothiazole and benzotriazole are given.
Copending patent application U.S. Ser. No. 348,521 relates to the use of higher alkylbenzotriazoles as copper and copper alloy corrosion inhibitors, and copending patent application U.S. Ser. No. 348,532 relates to the use of alkoxybenzotriazoles as copper and copper alloy corrosion inhibitors.
U.S. Pat. No. 4,406,811 discloses compositions containing a triazole such as tolyltriazole benzotriazole or mercaptobenzothiazole, an aliphatic mono- or di-carboxylic acid and a nonionic wetting agent.
U.S. Pat. No. 4,873,139 discloses the use of 1-phenyl-IH-tetrazole-5-thiol to prepare corrosion-resistant silver and copper surfaces. The use of 1-phenyl-5-mercaptotetrazole to inhibit the corrosion of carbon steel in nitric acid solutions is also known. See Chemical Abstract CA 95(6):47253 m (1979).
The present invention relates to compositions comprising: a) 1-phenyl-5-mercaptotetrazole, an isomer of 1-phenyl-5-mercaptotetrazole, a substituted phenyl mercaptotetrazole or a salt thereof; and b) a compound selected from the group consisting of tolyltriazole, benzotriazole and salts thereof, and the use of such compositions as corrosion inhibitors, particularly copper and copper alloy corrosion inhibitors. These compositions provide effective passivation of metallic surfaces, particularly copper and copper alloy surfaces, in contact with aqueous systems, and are especially effective in high dissolved solids water.
More particularly, the use of the instant compositions provides improved corrosion protection of copper-containing metals. As used herein the term "passivation" refers to the formation of a film on a metallic surface which is being protected from corrosion. "Passivation rate" refers to the time required to form a protective film on a metallic surface, and "persistency" refers to the length of time a protective film is present in the absence of a corrosion inhibitor. Also, the term "high solids water" refers to water which contains quantities of solids, particularly dissolved solids, in excess of about 1500 mg/L.
The instant compositions are not known or suggested in the art.